Center punch



P 11, 1956 w. w. MORRIS ETAL 2,762,435

CENTER PUNCH Filed March 12, 1954 FIG. .1.

FIG 2.

INVENTOR.

United States Patent CENTER PUNCH Walter W. Morris and Marie A. Morris, Detroit, Mich.

Application March 12, 1954, Serial No. 415,828

2 Claims. (Cl. 164- 1235) This invention relates to improvements in -"impact driven center punches for tool and die work.

An object of the invention is to provide an improved impact driven center punch for tool and die work which may be operated with one hand.

Another object of the invention is to provide an improved center punch of the character indicated above which is operated by a trigger and which automatically resets itself in operative condition after each use.

Another object of the invention is to provide a center punch of the character indicated above which is inexpensive of construction and simple and convenient to use.

Other objects and advantages of the invention will be apparent from the ensuing description considered in conjunction with the attached drawing, in which:

Figure l is a plan view of an embodiment of the present invention;

Figure 2 is a longitudinal section taken along the line 22 of Figure 1; and

Figure 3 is a transverse section taken along the line 33 of Figure 2.

Referring more particularly to the drawings, numeral 1 designates a hollow pistol-shaped body consisting of two matching half sections fastened together by bolts 2. The body includes a barrel 3 formed integral therewith. A punch element 4 extends longitudinally from one end of the barrel 3 and is connected to the barrel 3 for limited longitudinal movement therein by a stop screw 5 which extends transversely through the side of the barrel 3 and is slidably received in a closed slot 6 formed in and extending longitudinally of the punch element 4.

A hammer 7 is positioned within the barrel 3 intermediate the punch element 4 and the other end of the barrel 3 and is slidably supported therein. The hammer 7 is provided with an annular notch 8 intermediate its ends. Also within the barrel 3 is a coil spring 9 having one end abutting the inner face of a winged bolt 10 which closes the other end of the barrel 3. The spring is compressed between the bolt 10 and the hammer 7 and biases the hammer toward and against the punch element 4.

Positioned within the handle portion of the body 1 is a trigger means releasably engaged with the hammer 7 for holding the latter against the biasing efiect of the spring 9. The trigger means consists of two spring biased discs 11 and 12 positioned within said handle portion and interengaging each other.

The disc 11 is connected to the handle portion for rotary movement about a fixed pin 13 which extends across the handle portion. The disc 12 is also connected to the handle portion for rotary movement about a pin 14 which extends across the handle portion, the disc 12 being free to move forwardly and rearwardly relative to the pin 14, this movement being limited by the closed slot 15 provided in the central part of the disc 12.

A sear 16, pivoted at 17 to the disc 11, releasably Patented Sept. 11,1956

engages the hammer 7 in the annular notch 8. One edge 18 of the sear 16 is curved longitudinally as a cam to make sliding contact with the beveled edge 19 of the notch 8. A bent leaf spring 20 is positioned against the opposite edge of the sear 16 to bias the sear to the hammer engaging position.

The disc 12 has a fixed trigger 21 which projects exteriorly of the handle portion through the slot 22. A curved trigger guard 23 is secured at either end to the outer surface of the handle portion 1 and spans but is spaced from the slot 22 and the finger piece 21 and protects the trigger 21 from accidental contact. .The disc 12 also has a fixed dog 24 which rockingly seatsin an indentation 25 in the periphery of the-disc 11.

A leaf spring 26 has one end engagedagainst the inner surface of the handle portion and is bent around a pin 27 fixed to the handle portion and has its other end lockably engaged in an indentation 28 in the disc 11, thereby biasing the disc 11 in a counterclockwise direc-: tion. A leaf spring 29 has one end engaged with a part of the handle portion remote from the spring 26, extends between guides 30 and has its other end engaged in an indentation 31 in the disc 12, biasing the latter disc in the clockwise direction.

An individual using the punch grasps the handle portion in one hand, forefinger on the trigger 21, and places the forward end of the punch element 4 against the work at the point to be punched. The pressure of the punch 4 against the work pushes the punch 4 inwardly of the barrel 3 to its extreme retracted position in which the forward end of the slot 6 is against the stop screw 5. The user then pulls the trigger 21 so as to rotate the disc 12 counterclockwise against the resistance of the spring 29, so that the pawl 24 engaged in the indentation 25 causes the disc 11 to rotate clockwise against the resistance of the spring 26. Clockwise rotation of the disc 11 causes the sear 16 to move the plunger 7 rearwardly against the resistance of the spring 9 and the curved edge 18 of the sear 16 to slide upon the beveled edge 19 of the notch 8 until the engaged end of the sear 16 slips from the notch 8. The spring 9, thus freed, drives the hammer 7 forwardly so that it strikes the adjacent end of the punch 4 and drives the forward end of the punch 4 into the work. When the users finger is removed from the trigger 21, the spring 29 returns the disc 12 and the trigger 21 to their starting positions, and the spring 26 causes the disc 11 to turn counterclockwise until the sear 16, held yieldingly in an outstanding position from the disc 11 by the spring 20, slips back into the notch 8 and the punch is ready for reuse. As will be noted, the operation of the punch requires only one hand.

What is claimed is:

1. In an impact driven punch, a pistol shaped hollow body having a barrel and a handle portion, a punch element slidably confined in said barrel, said punch element having a forward end projecting beyond one end of the barrel and a rear end spaced from but within the other end of the barrel, pin and slot means acting between the punch element and the barrel and limiting longitudinal movement of the punch element relative to the barrel, a hammer slidably confined in the barrel between the rear end of the punch element and the said other end of the barrel, an expanding spring confined within the barrel and compressed between the said other end of the barrel and the hammer, said hammer having a notch, and combined trigger and cocking mechanism within said handle portion, said mechanism including a scar engaging in the hammer notch in the cocked posi tion of the hammer, in which the hammer is retracted rearwardly and the spring is compressed, and a trigger exposed outside of the handle portion, said trigger being movable in one direction to withdraw the sear from the hammer notch.

2. In an impact driven punch, a pistol shaped hollow body having a barrel and a handle portion, a punch element slidably confined in said barrel, said punch element having a forward end projecting beyond one .end of the barrel and a rear end spaced from but within the other end of the barrel, pin and slot means acting between the punch element and the barrel and limiting longitudinal movement of the punch, element relative to the barrel, a hammer slidably confined in the barrel between the rear end of the punch element and the'said other end of the barrel, an expanding spring confined within the barrel and compressed between the said ,otherend of the barrel and the hammer, said hammer having a notch, and combined trigger andcocking mechanism within said handle portion, said mechanism including a sear engaging in the hammer notch in the cocked position of the hammer, in which the hammer is retracted rearwardly and the spring is compressed, and a triggerexposed outside of the handle portion, said trigger being movable in one direction towithdraw the sear from the hammer notch, said combined mechanism comprising a first rotary disc mounted in said handle portion, said sear being resiliently mounted on said first disc, a first cocking spring acting between said handle portion and said first disc and biasing said first disc in one direction of rotation, a second rotary disc mounted in said handle portion, said second disc being capable of rotation and of limited forward and rearward movement relative to said handle portion a second cocking spring acting between said handle portion and said second disc and biasing said second disc in a direction of rotation opposite that of said first disc and in a rearward longitudinal direction, and a dog on said second disc operatively engaging said first disc, said trigger being fixed on said second disc.

References Cited in the file of this patent UNITED STATES PATENTS Re, 6,817 Dean Dec. 21, 1875 913,677 Ainsworth Mar. 2, 1909 1,569,153 Temple Jan. 12, 1926 1,977,362 Wakstein Oct. 16, 1934 

